1. Field of the Invention
This invention relates generally to fiber optic connections and is concerned more particularly with a method and means for coupling one end of an optical fiber element to another light operative device.
2. Discussion of the Prior Art
A fiber optic cable may be of the single conduit type comprising a filamentary optical fiber made of flexible light-pipe material, such as glass, for example, and provided with a buffer coating of flexible material, such as opaque plastic material, for example. The coated optical fiber may be laid axially with a stiffening wire of flexible tension-resistant material, such as steel, for example; and the combination encircled by a protective jacket of flexible material, such as rugged plastic material, for example. Thus, the single conduit fiber optic cable resembles, in appearance, a single conductor electrical cable having an insulation coated wire and an uninsulated ground wire encircled by a protective jacket of flexible material.
This similarity of the single conduit fiber optic cable to the single conductor electrical cable also may extend to its use and installation. For example, the optical fiber element of the fiber optic cable may be employed for transmitting informational data from a source to a receptor device in the form of light pulses, just as the insulation coated wire of the electrical cable may be employed for conducting the informational data by means of electrical pulses. Also, the single conduit fiber optic cable may have its end portions secured to respective connectors for coupling the optical fiber element to the source and to the receptor device for transmitting light energy efficiently from the source to the fiber optic cable and from the fiber optic cable to the receptor device. Furthermore, when the source is located from the receptor device a distance greater than the length of one fiber optic cable, a coupler device may be provided for coupling a connector at one end of the fiber optic cable to a connector at an adjacent end of another fiber optic cable in a manner which promotes efficient transmission of light energy from one to the other of the fiber optic cables.
To minimize losses in light energy entering and leaving the fiber optic cable, the terminal end surfaces of the optical fiber generally are made mirror flat, as by polishing, for example, and are disposed substantially perpendicular to the axis of the fiber. Also, in order to maintain these end surfaces mirror flat and perpendicular, as described, the terminal end surfaces of the optical fiber are not disposed in butting engagement with a connecting component but, instead, are spaced therefrom a predetermined distance, such as thousandth to ten thousandths of an inch, for example. Consequently, after the terminal end surfaces of the optical fiber have been prepared as described, the connectors generally are mounted on respective end portions of the fiber optic cable and secured to the optical fiber, as by bonding, for example, so that the terminal end surfaces are fixed in relation to preselected portions, such as positive-stop shoulders, for example, of the connectors.
However, the bonding process for securing the connector to the glass optical fiber generally requires a curing time which is impractical for field use. In addition, the connectors generally are provided with a complex internal structure for ensuring that the terminal end surfaces of the secured optical fiber are spaced the predetermined distance from the connecting components. Moreover, a coupler device for coupling two of the connectors such that the secured optical fibers have respective terminal end surfaces spaced the predetermined distance from one another may require an intermediate spacer device, such as a washer, for example, which may become separated from the coupler device and lost.